Well, first off, since NewEgg doesn't make RAM, you should take the manuf. number and go hunt down the RAM makers on the web and read their white-papers for all the technical nitty-gritty...

Second, the difference is that one's more dense than the other.

Sorry, couldn't resist.

Anyway, low-density chips usually mean that the chance for a "missed charge" is lower than with a higher-density chip, because the cells are further apart. However, higher-density chips run faster and are more efficient.

That's a REALLY REALLY REALLY thick layman's explanation...but you get the picture.

well I had someone ask this question some time back and his was regarding PC-133 RAM and the deal with it was if your RAM slot supports ike 1gb in just one single slot, then that slot can take high density RAM, but lets say one slot was only able to fit in 512mb low density.

he was wondering if the high density would work in his board and I looked it up and got that information. That the actual slot has to have a certain amount of memory it can handle for it to be high density.